1. Field of the Invention
The present invention relates to a paper transfer assisting mechanism for ensuring that elongated paper is properly fed and transferred along a predetermined transfer path. The present invention also relates to a paper transfer apparatus incorporating such a paper transfer assisting mechanism.
2. Description of the Related Art
Conventionally, use has been made of e.g. an electrophotographic apparatus for printing selected images on elongated recording paper. Typically, the elongated paper may be divided into a series of continuous recording segments defined by plural lines of perforations formed in the elongated paper. Recently, in order to meet the needs for more effective printing operation, such elongated paper may need to be transferred at high speed (1,000 mm/s for example).
For transferring the elongated paper along a predetermined path, an electrophotographic apparatus may incorporate a paper transfer mechanism. The high-speed paper transfer may be possible by improving the paper transfer mechanism.
A conventional paper transfer mechanism may include a paper guide plate arranged along the transfer path for guiding the recording paper, and a traction mechanism for moving the recording paper along the transfer path. The traction mechanism may be arranged adjacent to an image transfer processing section of the electrophotographic apparatus. The traction mechanism may be provided with a plurality of movable engaging projections or claws coming into engagement with feed holes of the recording paper. The feed holes are arranged in two rows each extending along a corresponding one of the longitudinal edges of the recording paper. When the paper transfer mechanism is actuated, with the engaging claws held in engagement with the feed holes, the recording paper is advanced along the transfer path. In addition to the traction mechanism, the paper transfer mechanism may include a paper feed roller for feeding the recording paper from a paper feeding section into the transfer path. The paper feed roller may be arranged adjacent to the paper feeding section. Further, the paper transfer mechanism may include a paper container to be placed at the paper feeding section. The paper container is arranged to hold the recording paper in a neatly folded manner.
With such an arrangement, upon rotation of the paper feed roller, the elongated paper accommodated in the paper container is led onto the transfer path. Thereafter, while properly guided by the paper guide plate, the elongated paper is forwarded further along the transfer path. After passing by the paper guide plate, the recording paper is moved forward by the traction mechanism. As previously described, the traction mechanism includes movable claws coming into engagement with the feed holes arranged along the longitudinal edges of the elongated paper. Thus, when the elongated paper is moved by the traction mechanism, the elongated paper will not deviate laterally (and longitudinally) from the transfer path. After passing by the traction mechanism, the recording paper may be brought to a terminal section arranged at the end of the transfer path. At the terminal section, like at the paper feeding section, the recording paper may be held in a neatly folded manner.
In the paper transfer mechanism having the above arrangements and functions, higher transfer speed of the recording paper may be attained by increasing the operation speeds of the traction mechanism and the paper feed roller. Here, by causing the operation speed of the paper feed roller to differ from that of the traction mechanism, the recording paper can be transferred properly (for example, without sagging).
Instead of using the elongated paper with feed holes, use may be made of elongated recording paper having no feed holes. In this case, suitable transfer rollers may be used in place of the traction mechanism described above.
The conventional paper transfer mechanism has been found disadvantageous in the following points.
First, in the conventional transfer mechanism, no means for preventing deviation of the paper is provided between the paper feeding section and the image transfer section. Thus, as transferred between the above sections, the elongated paper may unduly sway relative to the transfer path or take an oblique posture relative to the transfer path. Such an unfavorable transfer behavior of the recording paper may adversely affect the image forming performance onto the elongated paper at the image transfer section.
The above disadvantage may be addressed by providing e.g. guide plates on both sides of the transfer path. However, such guide plates may easily be worn out through contact with the recording paper transferred at high speed. As a result, guide plates may need to be replaced frequently, which is disadvantageous in terms of costs.